From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4A4E3C433F5 for ; Fri, 21 Jan 2022 17:21:58 +0000 (UTC) Received: from localhost ([::1]:55586 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nAxbp-0001SD-BM for qemu-devel@archiver.kernel.org; Fri, 21 Jan 2022 12:21:57 -0500 Received: from eggs.gnu.org ([209.51.188.92]:39824) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nAxMe-0007Os-UR for qemu-devel@nongnu.org; Fri, 21 Jan 2022 12:06:16 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:57589) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nAxMc-00088U-Jn for qemu-devel@nongnu.org; Fri, 21 Jan 2022 12:06:16 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1642784774; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=H/rSdy/5y0mBkG/g1Vy1IxuIA0BEht/KzFGLGKJHiGw=; b=S0lyz3nE8uYoSdhv//RT9auy/P4zbe+A2LByixDGu6QdA6FmNrXuAevYO3vupsjeW5LiY1 hsSXfm3c8Pz4vGhnu0VnL6gpXlsEz89nbPjQwcUZ0NMNAQjwrMPDuYEY8iXvLdEUzccjLh fmznQIYokAkA5GFG3LQm6c6vM62fT3I= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-106-qvdqd97sMEygne_wUlldxA-1; Fri, 21 Jan 2022 12:06:08 -0500 X-MC-Unique: qvdqd97sMEygne_wUlldxA-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 1E42B86A079; Fri, 21 Jan 2022 17:06:06 +0000 (UTC) Received: from virtlab701.virt.lab.eng.bos.redhat.com (virtlab701.virt.lab.eng.bos.redhat.com [10.19.152.228]) by smtp.corp.redhat.com (Postfix) with ESMTP id 6E7DB7EBE0; Fri, 21 Jan 2022 17:06:04 +0000 (UTC) From: Emanuele Giuseppe Esposito To: qemu-block@nongnu.org Subject: [PATCH v6 04/33] block/export/fuse.c: allow writable exports to take RESIZE permission Date: Fri, 21 Jan 2022 12:05:15 -0500 Message-Id: <20220121170544.2049944-5-eesposit@redhat.com> In-Reply-To: <20220121170544.2049944-1-eesposit@redhat.com> References: <20220121170544.2049944-1-eesposit@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=eesposit@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset="US-ASCII" Received-SPF: pass client-ip=170.10.133.124; envelope-from=eesposit@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.699, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Fam Zheng , qemu-devel@nongnu.org, "Denis V. Lunev" , Eric Blake , Emanuele Giuseppe Esposito , Juan Quintela , Daniel Henrique Barboza , Markus Armbruster , Eduardo Habkost , Richard Henderson , Greg Kurz , "Dr. David Alan Gilbert" , =?UTF-8?q?C=C3=A9dric=20Le=20Goater?= , Stefan Hajnoczi , John Snow , David Gibson , Kevin Wolf , Vladimir Sementsov-Ogievskiy , =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , Hanna Reitz , qemu-ppc@nongnu.org, Paolo Bonzini Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Allow writable exports to get BLK_PERM_RESIZE permission from creation, in fuse_export_create(). In this way, there is no need to give the permission in fuse_do_truncate(), which might be run in an iothread. Permissions should be set only in the main thread, so in any case if an iothread tries to set RESIZE, it will be blocked. Also assert in fuse_do_truncate that if we give the RESIZE permission we can then restore the original ones, since we don't check the return value of blk_set_perm. Signed-off-by: Emanuele Giuseppe Esposito --- block/export/fuse.c | 25 ++++++++++++++++++------- 1 file changed, 18 insertions(+), 7 deletions(-) diff --git a/block/export/fuse.c b/block/export/fuse.c index 823c126d23..3c177b9e67 100644 --- a/block/export/fuse.c +++ b/block/export/fuse.c @@ -86,8 +86,8 @@ static int fuse_export_create(BlockExport *blk_exp, assert(blk_exp_args->type == BLOCK_EXPORT_TYPE_FUSE); - /* For growable exports, take the RESIZE permission */ - if (args->growable) { + /* For growable and writable exports, take the RESIZE permission */ + if (args->growable || blk_exp_args->writable) { uint64_t blk_perm, blk_shared_perm; blk_get_perm(exp->common.blk, &blk_perm, &blk_shared_perm); @@ -392,14 +392,23 @@ static int fuse_do_truncate(const FuseExport *exp, int64_t size, { uint64_t blk_perm, blk_shared_perm; BdrvRequestFlags truncate_flags = 0; - int ret; + bool add_resize_perm; + int ret, ret_check; + + /* Growable and writable exports have a permanent RESIZE permission */ + add_resize_perm = !exp->growable && !exp->writable; if (req_zero_write) { truncate_flags |= BDRV_REQ_ZERO_WRITE; } - /* Growable exports have a permanent RESIZE permission */ - if (!exp->growable) { + if (add_resize_perm) { + + if (!qemu_in_main_thread()) { + /* Changing permissions like below only works in the main thread */ + return -EPERM; + } + blk_get_perm(exp->common.blk, &blk_perm, &blk_shared_perm); ret = blk_set_perm(exp->common.blk, blk_perm | BLK_PERM_RESIZE, @@ -412,9 +421,11 @@ static int fuse_do_truncate(const FuseExport *exp, int64_t size, ret = blk_truncate(exp->common.blk, size, true, prealloc, truncate_flags, NULL); - if (!exp->growable) { + if (add_resize_perm) { /* Must succeed, because we are only giving up the RESIZE permission */ - blk_set_perm(exp->common.blk, blk_perm, blk_shared_perm, &error_abort); + ret_check = blk_set_perm(exp->common.blk, blk_perm, + blk_shared_perm, &error_abort); + assert(ret_check == 0); } return ret; -- 2.31.1